Internal surface of a container



FIG. 1 is a top left front perspective view of an internal surface of a container showing my new design;

The broken lines(s) which define the bounds of the claimed design form no part thereof.

FIG. 2 is a front elevational view thereof; and,

FIG. 3 is a top plan view thereof. 

The ornamental design for an internal surface of a container, as shown and described. 